Technical Field
The present application relates to electronic toll collection (ETC) systems and, in particular, to methods for prolonging battery life in toll transponders and to transponders implementing such methods.
Background Art
In Electronic Toll Collection (ETC) systems, Automatic Vehicle Identification (AVI) is achieved by the use of Radio Frequency (“RF”) communications between roadside readers and transponders within vehicles. Each reader emits a coded identification signal, and when a transponder enters into communication range and detects the reader, the transponder sends a response signal. The response signal contains transponder identification information, including a unique transponder ID.
Active transponders contain a battery that powers the transponder. The manufacturers of transponders generally equip the transponder with a battery sized to provide the transponder with sufficient power to last for a number of years. In some cases, the manufacturers may guarantee that the transponder will last for a minimum number of years. The guarantee may be based on a calculated average number of trigger-read cycles for normal use of the transponder in ETC systems.
ETC transponders are now being leveraged for additional applications. For example, in some cases additional roadside readers may be used to count vehicles for traffic monitoring and management purposes. In some cases, toll transponders may be used for parking or other electronic payment transactions. In some situations, these additional uses are being implemented by third parties and not the original ETC infrastructure provider. Accordingly, toll transponders may end up being polled more often that might be anticipated by the ETC infrastructure provider, particularly when a transponder-equipped vehicle is parked or idling near a reader (whether an ETC reader or another type of reader). This can result in far more trigger-read cycles than was originally anticipated by the ETC infrastructure provider, and will negatively impact the lifespan of the toll transponder battery.
It would be advantageous to improve the battery life a toll transponder.